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Bachmann Farish Split Gears in Diesels


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I took out my recently purchased Farish Class 44 D7 "Ingleborough" to run last night and oh what a noise! once it was on the track. That classic click-click-click-click and awful running which all N-gauge modelers know means a split gear. In this instance the split was easy to find because it was so big. I've attached a picture.

 

post-4367-0-00537200-1322150844_thumb.jpg

 

This is my fifth split gear on a new Bachmann engineered Farish model within about 4 years. I didn't keep detailed records, but one was on a Class 25 and two were on two different Peaks.

 

Just curious if other people have had the same problem, and with what frequency.

 

Matt

Edited by oreamnos
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Hi Guys;

 

I have had a few...a couple on Class 66s and a couple on Class 57s. Couldn't convince Bachmann to replace then FOC though so I bought a set of 6 and have used 2 of them. I rewheeled the 57 with standard size wheels & gears (the 57 wheel diameter is larger) and opened out the covered gears on the underside of the bogie for clearance.

 

As for the 20s.....every single one that has passed through my workbench has had all the idlers (12 tooth gear next to the axles) split. That's 4 per loco!!! Here's hoping the new 20 has a better arrangement.

 

Later;

STU in KNID

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I've had all the idlers go on 4 of my 5 class 20s (I replaced the others before they split).

 

Like Robert I replaced them with ones from the NGS and opened out the hole. Fingers crossed nothing else has gone wrong.

 

Happy modelling.

 

Steven B.

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The only locos I've had split gear problems with are the Farish Westerns. All the other old Farish types I have left - a Class 47 and a Class 40 chassis under a resin Peak body have run OK for years. Both Westerns continually split gears until I lost patience - the blue one is sidelined in storage and the maroon now has a Lifelike chassis underneath it.

 

STEVE

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I've had this very recently with both a cl.57 (which has been reported as quite common) and also now on a cl.60. Both these locos had been in store for some time. While I was able to get some replacement gears from Bachmann free of charge (by pointing out that it constituted a design flaw present at time of manufacture), only on the cl.57 was I actually able to get the wheelset apart to replace the gear! On the cl.60 this seems impossible (probably only by using a gear puller) so I've ordered a new axle with gears from BR lines.

 

I certainly wasn't expecting to find this on a cl.60, which is a relatively new Bachmann era product (whereas the cl.57 was quite early and it is a common problem - and I guess the reason for so many cl57s on Bachmann's "returned" bargain pile at Warley). Perhaps they still aren't over the design flaw? You never hear about this on continental brands!

 

Justin

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Perhaps they still aren't over the design flaw? You never hear about this on continental brands!

 

Nor with Kato, Atlas, or Life-Like in the US. I remember there was great hope and fanfare when Bachmann introduced the new chassis for the old Poole diesels that its "new, thicker gears" would eliminate this old problem. Clearly this was unfounded.

 

I am a bit stunned by the number of replies to my OP. Even more stunned to hear this problem affects more recent models such as the 57, 60, and 66. This type of problem should be a "no-brainer" to eliminate. I don't understand why Bachmann can't solve it when its global competitors have.

 

I rarely read US outline bulletin boards these days but I wonder if Bachmann's US outline locos have the same problem with split gears?

 

Matt

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Bachmann are not allowed to fix the problem, otherwise North West Short Line would not be able to run a business by replacing their rubbish gears with metal replacements :mosking:

 

And yes, Bachmann's US geared locomotives all have poor plastic gears and NWSL make metal replacements for them. In fact it is worth taking a look at the NWSL catalogue to see just hown many replacement gear sets they make, and it is not just Bachmann they make them for.

 

The problem is not limited to them, however, the venerable SPUD suffers from the problem, as do many European mechanisms.

Edited by hollywoodfoundry
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I had a similar issue on my large fleet

During the acquisition process I tested each model and was found to be in working order

They were then placed into storage which was an uncontrolled environment

On removal and retesting many were found to have split gears, which my previous records showed had not been obvious

 

All the models are now in a controlled environment and there has not been one such failure

The room is stablised at 18'C

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I believe the reason for this is that the gear material, usually Acetal or otherwise known as Delrin, takes some time to settle and cure after being moulded. During this time it shrinks, and if it is forced onto an axle before the curing has finished, it will split some time later when it finally shrinks.

 

One way to avoid this is to machine fine splines into the axle, so the fit does not have to be so tight, and this will usually prevent splittting.

Edited by hollywoodfoundry
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I had a similar issue on my large fleet

During the acquisition process I tested each model and was found to be in working order

They were then placed into storage which was an uncontrolled environment

On removal and retesting many were found to have split gears, which my previous records showed had not been obvious

 

All the models are now in a controlled environment and there has not been one such failure

The room is stablised at 18'C

 

I had a similar experience when I stored all my locos, (mainly Farish diesels), in a well insulated loft space that is freezing in winter a very hot in summer. Following 2 years storage around 40% of the locos were found to have suffered split gears. 5 years later with all the locos now kept in a 'normal' temperature range room I have not had any recurrence of the split gear problem.

 

I accept I might be jumping to conclusions as it could be just a pure coincidence but I'll never again risk 'N' gauge loco storage in a widely fluctuating temperature environment. Hope this may be of use to others.

 

HC

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Split gears affected more Poole-made models and over the years when I owned them I had to replace quite a few wheelsets because of that problem.

I'm surprised it's still an issue with Bachmann Farish locos although even so I had my fair share of gears working loose on axles, though never had any gears that actually split.

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Were all these problems with Bachmann Farish or did some apply to Poole-made stuff?

Like everyone else, I've had my fair share of split gears with the Poole-made stuff, but all 5 split gears I was writing about in my OP were all in post Bachmann takeover, made in China models.

 

Matt

Edited by oreamnos
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Just taken apart the second 66 I referred to above and the gears appear to be OK. On a light engine test run the clicking has gone - so perhaps it was a lump of something in one of the gear teeth or perhaps the worm gear jumping when it is under load. Getting too cold out there to test under load tonight!

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I've had this problem on Class 57s and 66s. Plus on Class 158 DMUs. The plastic seems very temperature sensitive. Plus I think a little bit of dirt can act as a trigger to put the teeth under a little more pressure, which triggers the crack.

 

Its not a great advert for N Gauge. Somehow I cannot see them returning to brass gears like on my early Farish Class 37! It would be useful if replacement metal gears where available, to make the locos more robust. Its a reason I tend to minimise the number of locos I own :O

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Somehow I cannot see them returning to brass gears like on my early Farish Class 37!

 

With good reason - Brass on brass is a bad engineering choice - the reason they were dropped in the first place is that the brass wears out worm gears and the metal on metal is noisier.

 

Cheers,

Alan

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I guess the other cause of gear splits is the interference fit of the gear on the axle been a little to tight. This puts the gear under stress, which eventually with expansion and contraction as temperature fluctuates, causes them to fail, as others have suggested.

 

Wonder if a solution would be to remove the gear, relieve the gears hole and loctite them in place.

Edited by richierich
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